Benzo[b]perhydroheterocyclic arylamines and lubricating oil compositions

ABSTRACT

Benzo[b]perhydroheterocyclic arylamine compounds have shown to be particularly useful as stabilizers. The compounds may serve as antioxidants, antiozoants, heat stabilizers and ultraviolet light stabilizers and such compounds are oil soluble, thus particularly suited for use as an antioxidant in a lubricating oil composition.

FIELD OF THE INVENTION

Benzo[b]perhydroheterocyclic arylamines compounds have demonstratedutility in mitigating oxidation in functional fluids. Accordingly, thepresent invention is directed to substituted and unsubstitutedBenzo[b]perhydroheterocyclic arylamines compounds and lubricatingcompositions containing such.

BACKGROUND OF THE INVENTION

Diarylamine antioxidants are known and have been widely used to improvethe thermal-oxidative stability and/or light induced degradation innumerous products used in engineering; for example, they can improve theperformance properties in lubricants, hydraulic fluids, metal workingfluids, fuels or polymers, just to name a few.

Commonly, these diarylamines have been alkylated, see for example, U.S.Pat. No. 2,943,112 which discloses an improved process for alkylatingdiphenylamine and U.S. Pat. No. 3,655,559 which discloses alkylateddiphenylamines as stabilizers. Alkaryl substituted diphenylamines andphenylnapthylamines (such as α-methylstyryl-diphenylamine) are disclosedfor example in U.S. Pat. Nos. 3,533,992; 3,452,056 and 3,660,290.Substituted paraphenylene diamines have also been disclosed asantioxidants for lubricants in which iron-catalyzed oxidation reactioncan occur, see U.S. Pat. No. 5,232,614.

Additionally, alkyl substituted 1,2-dihydroquinoline and polymersthereof, have been employed as antioxidants, see U.S. Pat. Nos.3,910,918. While, U.S. Pat. No. 5,310,491 discloses the reaction productof an alkyl substituted 1,2-dihydroquinoline with a diarylamine.Tetrahydroquinones and substituted tetrahydroquinones have also havealso been disclosed as antioxidants, see for example U.S. Pat. Nos.2,794,020; 3,362,929; 4,692,258 and 4,965,006. Likewisedecahydroquinolines and substituted decahydroquinolines have beenemployed as antioxidants, see U.S. Pat. Nos. 2,998,468 and 4,069,195.

In order to satisfy the more severe operating conditions and newapplications which require improved oxidation inhibition, continueddevelopment of new compounds to mitigate oxidation is of paramountinterest. The compounds of the present invention demonstrate superiorperformance in an organic substrate and thus may serve the continuedneed.

SUMMARY OF THE INVENTION

The present invention is directed in part to compounds which may serveas antioxidants, antiozoants, heat stabilizers and ultraviolet lightstabilizers and such compounds are oil soluble, thus particularly suitedfor use as an antioxidant in a lubricating oil composition. Accordingly,the present invention discloses a compound according to formula I:

wherein

R₁ and R₂ are each independently selected from the group consisting ofhydrogen, alkyl from 1 to 20 carbon atoms, —OR, —SR and —NRR′, where Rand R′ are independently hydrogen or alkyl from 1 to 6 carbon atoms, orR₁ and R₂ when adjacent to each other together form a 5 to 6 memberedalicyclic or aromatic ring which may be optionally substituted with 1 or2 alkyl groups each having from 1 to 20 carbon atoms;

each R₃ is hydrogen or alkyl from 1 to 6 carbon atoms,

X and X′ are independently selected from —CHR₄—, oxygen, sulfur or NR₅,wherein R₄ and R₅ are independently hydrogen or alkyl from 1 to 6 carbonatoms, with the proviso that at least one of X or X′ is a heteroatompositioned ortho or para to the bridging nitrogen atom, and when X or X′are nitrogen then R₁ or R₂ is not hydroxyl; and further provided thatwhen one of X or X′ is —CHR₄— then the other may not be oxygen; and n isan integer from 1 to 2.

The benzo[b]perhydroheterocycle can contain one or two heteroatoms andpreferably contains at least one nitrogen or oxygen atom, with nitrogenbeing particularly preferred, thus in this aspect at least one X or X′is oxygen of NR₅, with —NH— being particularly preferred. The singlenitrogen benzo[b]perhydroheterocycle can be characterized as havingbeing unsubstituted on the heterocyclic ring but, optionally substitutedon the aryl ring, thus R₁ and R₂ are each independently selected fromthe group consisting of hydrogen, alkyl from 1 to 20 carbon atoms, —OR,—SR and —NRR′, where R and R′ are independently hydrogen or alkyl from 1to 6 carbon atoms, or R₁ and R₂ when adjacent to each other togetherform a 5 to 6 membered alicyclic or aromatic ring which may beoptionally substituted with 1 or 2 alkyl groups each having from 1 to 20carbon atoms, and more particularly wherein R₁ and R₂ are eachindependently selected from the group consisting of hydrogen and alkylfrom 1 to 20 carbon atoms.

In yet another aspect, X and X′ are independently selected from oxygen,sulfur or NR₅, wherein R₅ is hydrogen or alkyl from 1 to 6 carbon atoms.Thus, both X and X′ can be oxygen or for example, nitrogen.

In the compounds of formula I, R₁ and R₂ together with the atoms betweenthem, can form alicyclic or aromatic ring. Thus, one aspect of thecompound is directed to when R₁ and R₂ are adjacent to each other andtogether form a 5 to 6 membered aromatic ring which may be optionallysubstituted with 1 or 2 alkyl groups each having from 1 to 20 carbonatoms. Other aspects are characterized for example, wherein R₁ ishydrogen and R₂ is selected from the group consisting of alkyl from 1 to20 carbon atoms, —OR, —SR and —NRR′, where R and R′ are independentlyhydrogen or alkyl from 1 to 6 carbon atoms, with the tertiary aminesbeing preferred.

Another aspect of this invention is directed to lubricating compositionscomprising a major amount of an oil of lubricating viscosity and acompound of formula I as described herein above.

DETAILED DESCRIPTION OF THE INVENTION

Inhibition of free radical-mediated oxidation is one of the mostimportant reactions in organic substrates and is commonly used inrubbers, polymers and lubrication oils; namely, since these chemicalproducts may undergo oxidative damage by the autoxidation process.Hydrocarbon oxidation is a three step process which comprises:initiation, propagation and termination. Oxidative degradation and thereaction mechanisms are dependent upon the specific hydrocarbons,temperatures, operating conditions, catalysts such as metals, etc.,which more detail can be found in Chapter 4 of Mortier R. M. et al.,1992, “Chemistry and Technology of Lubricants Initiation”, VCHPublishers, Inc.; incorporated herein by reference in its entirety.Initiation involves the reaction of oxygen or nitrogen oxides (NO_(x))on a hydrocarbon molecule. Typically, initiation starts by theabstraction of hydrocarbon proton. This may result in the formation ofhydrogen peroxide (ROOH) and radicals such as alkyl radicals (R.) andperoxy radicals (ROO.). During the propagation stage, hydroperoxides maydecompose, either on their own or in the presence of catalysts such asmetal ions, to alkoxy radicals (RO.) and peroxy radicals. These radicalscan react with the hydrocarbons to form a variety of additional radicalsand reactive oxygen containing compounds such as alcohols, aldehydes,ketones and carboxylic acids; which again can further polymerize orcontinue chain propagation. Termination results from the selftermination of radicals or by reacting with oxidation inhibitors.

The uncatalyzed oxidation of hydrocarbons at temperatures of up to about120° C. primarily leads to alkyl-hydroperoxides, dialkylperoxides,alcohols, ketones; as well as the products which result from cleavage ofdihydroperoxides such as diketones, keto-aldehydes hydroxyketones and soforth. At higher temperatures (above 120° C.) the reaction rates areincreased and cleavage of the hydroperoxides plays a more importantrole. Additionally, at the higher temperatures, the viscosity of thebulk medium increases as a result of the polycondesation of thedifunctional oxygenated products formed in the primary oxidation phase.Further polycondesation and polymerization reaction of these highmolecular weight intermediates results in products which are no longersoluble in the hydrocarbon and form varnish like deposits and sludge.

Since autoxidation is a free-radical chain reaction, it therefore, canbe inhibited at the initiation and/or propagation steps. Typicaloxidation inhibition by diarylamines, such as dialkyldiphenylamine andN-phenyl-α-napthylamine, also involves radical scavenging. The transferof hydrogen from the NH group of the amine to the peroxide radicalsresults in the formation of a diarylamino radical which is resonancestabilized, thus prevents new chains from forming. A secondary peroxyradical or hydroperoxide can react with the diarylamino radical to formthe nitroxy radical, which is also a very potent inhibitor. Increaseddemands have been placed on many functional fluids which have in-turnplaced emphasis on new inhibitors.

The present invention is directed in part to aryl-amino bridgedbenzo[b]perhydroheterocyclic compounds particularly useful asstabilizers. The compounds may serve as antioxidants, antiozoants, heatstabilizers and ultraviolet light stabilizers and such compounds are oilsoluble, thus particularly suited for use an antioxidant in alubricating oil composition. Disclosed are particularly suited resonancestabilized inhibitor compounds according to formula I:

wherein: R₁ and R₂ are each independently selected from the groupconsisting of hydrogen, alkyl from 1 to 20 carbon atoms, —OR, —SR and—NRR′, where R and R′ are independently hydrogen or alkyl from 1 to 6carbon atoms, or R₁ and R₂ when adjacent to each other together from a 5to 6 member ring, said ring is selected from a 5 to 6 membered alicyclicring and a 5 to 6 membered aromatic ring, wherein said ring may beunsubstituted or substituted with 1 or 2 alkyl groups each having from 1to 20 carbon atoms; each R₃ is hydrogen or alkyl from 1 to 6 carbonatoms, X and X′ are independently selected from —CHR₄—, oxygen, sulfuror NR₅, wherein R₄ and R₅ are independently hydrogen or alkyl from 1 to6 carbon atoms, with the proviso that at least one of X or X′ is aheteroatom positioned ortho or para to the bridging nitrogen atom, andfurther provided that when one of X or X′ is —CHR₄— then the other maynot be oxygen, and when X or X′ are nitrogen then R₁ or R₂ is nothydroxyl; and n is an integer from 1 to 2. Nitrogen is a particularlypreferred heteroatom, which is more preferred than oxygen, which bothare more preferred than sulfur. Improved resonance stabilization may beaccomplished by substituents on the rings, thus particularly preferredgroups are electron donating groups, more so when positioned ortho andpara positions to the bridging nitrogen atom, thereby stabilizing thisamino radical. Therefore, one aspect of the present invention isdirected to where at least one R₁ and R₂ is —OR, —SR or —NRR′ with —NRR′being preferred. In another aspect, there is only a single substituenton the aryl group, thus R₁ is hydrogen with R₂ selected from —OR, —SR or—NRR′ with —NRR′ being preferred; wherein R and R′ are defined hereinabove and even more preferred, R is alkyl from 1 to 6 carbon atoms.

By way of an example, when X is selected to be the heteroatom, the orthoand para positions of X to the bridging nitrogen atom are depictedbelow.

The requirement for the ortho and para position are more prevalent whenX′ is CHR₄— which is a preferred embodiment. Additionally, R₁ and R₂,when other than hydrogen, are preferably positioned so that at least oneis in the ortho or para position to the bridging nitrogen atom.

In one preferred aspect, R₁ is hydrogen and R₂ is selected from thegroup consisting of alkyl from 1 to 20 carbon atoms, —OR, —SR and —NRR′,where R and R′ are independently hydrogen or alkyl from 1 to 6 carbonatoms; also preferred in the above, is where R is alkyl from 1 to 6.Preferably in the above, R₂ is positioned in the ortho or para positionto the bridging nitrogen atom. Alkyl chains have demonstrated improvedoil solubility in the resulting compound, therefore straight andbranched chain alkyl from 3 to 18 carbon atoms are particularlypreferred when the compounds are employed in lubricating oilcompositions. Nitrogen and oxygen heterocycles have demonstrated robustproperties and thus, preferably at least one X or X′ contains a nitrogenor oxygen atom, with nitrogen being particularly preferred, with singlenitrogen atom heterocycles even more preferred.

In another preferred aspect, R₁ and R₂ are each independently selectedfrom the group consisting of alkyl from 1 to 20 carbon atoms, —OR, —SRand —NRR′, where R is alkyl from 1 to 6 carbon atoms and R′ is hydrogenor alkyl from 1 to 6 carbon atoms. In another aspect, when R₁ and R₂ arelocated on adjacent carbon atoms, R₁ and R₂ together can form a 5 to 6membered alicyclic or aromatic ring which may be unsubstituted orsubstituted with 1 or 2 alkyl groups each having from 1 to 20 carbonatoms, preferably alkyl for 3 to 18 carbon atoms. Preferably at leastone X or X′ contains a nitrogen or oxygen atom, with nitrogen beingparticularly preferred, with single nitrogen atom heterocycles even morepreferred.

In formula I, particularly preferred compounds are depicted when atleast one X and X′ is selected from nitrogen or oxygen and even morepreferred is when at least one X and X′ is nitrogen. These nitrogencontaining benzo[b]perhydroheterocyclic compounds are further definedaccording to formula II

Accordingly, particularly preferred compounds are depicted by theFormula II below:

wherein R₁, R₂, R₃, R₅, X and n, are defined herein above, with theproviso the heterocyclic nitrogen is positioned ortho or para to thebridging nitrogen atom and further providing that when X is —CHR₄— thenR₁ and R₂ are not hydroxyl. As stated above, alkyl substituents havebeen employed to improve oil solubility and are particularly useful whenthere is greater than two heteroatoms in the compound. Preferably, ifthe compound is to contain alkyl groups, the alkyl groups arecharacterized in regard with R₁ or R₂. Thus preferably at least one R₁and R₂ are alkyl from 1 to 20 carbon atoms, —OR, —SR and —NRR′, where Ris alkyl from 1 to 6 carbon atoms and R′is defined above. Additionally,solubility may be increased in respect to R₁ and R₂ when R₁ and R₂ areadjacent to each other and can form a 5 to 6 membered alicyclic oraromatic ring which is substituted with 1 or 2 alkyl groups each havingfrom 1 to 20 carbon atoms. Even more preferred is that each R₃ and R₄when selected are all hydrogen.

Particularly preferred compounds of Formula II are depicted when n isequal to two. Even more preferred are the tetrahydro-quinolines, thus Xis —CHR₄— and the bridging ring nitrogen is attached at the 6 or 8position.

In Formula I, when n=1, the compounds can be depicted by Formula Iabelow:

wherein: R₁ and R₂ are each independently selected from the groupconsisting of hydrogen, alkyl from 1 to 20 carbon atoms, —OR, —SR and—NRR′, where R and R′ are independently hydrogen or alkyl from 1 to 6carbon atoms, or R₁ and R₂ when adjacent to each other together form a 5or 6 membered alicylic or aromatic ring which may be unsubstituted orsubstituted with 1 or 2 alkyl groups each having from 1 to 6 carbonatoms; R₃ is hydrogen or alkyl from 1 to 6 carbon atoms; X is oxygen,sulfur, —NH— or —N(alk)- where alk is alkyl from 1 to 6 carbon atomswith the proviso that the X heteroatom is positioned ortho or para tothe bridging nitrogen atom; X′ is selected from —CHR₄—, oxygen, sulfuror NR₅, wherein R₄ and R₅ are independently hydrogen or alkyl from 1 to6 carbon atoms, with the proviso that when X is oxygen then X′ isoxygen, sulfur or NR₅. Particularly suited benzo[b]perhydeoheterocyclicmoieties include substituted and unsubstituted: 2,3-dihydro-indole,2,3-dihydro-benzo[b]thiophene, 2,3-dihydro-benzoimidazole includingalkyl and dialkyl substituted dihydro-benzoimidazoles,2,3dihydro-benzooxazole, 2,3-dihydro-benzothiazole, benzo[1,3]dithiole,benzo[1,3]oxathiole and benzo[1,3]dioxole.

In Formula I, when n=2, particularly useful heterocyclic rings areselected from substituted and unsubstituted heterocyclic ringsconsisting of the group: 1,2,3,4-tetrahydroquinoline;1,2,3,4-tetrahydroqinoxaline; 3,4-dihydro-2H-benzo[1,4]thiazine;3,4-dihydro-2H-benzo[1,4]oxazine; thiochroman,2,3-dihydro-benzo[1,4]dithiine; 2,3-dihydro-benzo[1,4]oxathiine;2,3-dihydro-benzo[1,4]dioxine and chroman.

Particularly suited compounds of the present invention are exemplifiedherein below, therefore, another aspect of the present invention isdirected to the compounds comprising:phenyl-(1,2,3,4-tetrahydro-quinolin-6-yl)-amine;-(4-tert-butylphenyl)-1,2,3,4-tetrahydroquinolin-8-amine;N-2-naphthyl-1,2,3,4-tetrahydroquinolin-6-amine;N-2-naphthyl-1,2,3,4-tetrahydroquinolin-8-amine;N-(4-tert-butylphenyl)-2,3-dihydro-1-benzofuran-5-amine;N′-(2,3-dihydro-1-benzofuran-5-yl)-N,N-diethylbenzene-1,4-diamine;N-(4-tert-butylphenyl)-2,3-dihydro-1,4-benzodioxin-6-amine;N-(4-butylphenyl)-1,2,3,4-tetrahydroquinolin-8-amine.

The compounds of Formula I are particularly useful when employed in alubricating composition comprising the compound of Formula I with an oilof lubricating viscosity.

The lubricant compositions of this invention include a major amount ofbase oil of lubricating viscosity. Base Oil as used herein is defined asa base stock or blend of base stocks which is a lubricant component thatis produced by a single manufacturer to the same specifications(independent of feed source or manufacturer's location): that meets thesame manufacturer's specification; and that is identified by a uniqueformula, product identification number, or both. Base stocks may bemanufactured using a variety of different processes including but notlimited to distillation, solvent refining, hydrogen processing,oligomerization, esterification, and rerefining. Rerefined stock shallbe substantially free from materials introduced through manufacturing,contamination, or previous use. The base oil of this invention may beany natural or synthetic lubricating base oil fraction particularlythose having a kinematic viscosity at 100 degrees Centigrade (C) andabout 5 centistokes (cSt) to about 20 cSt, preferably about 7 cSt toabout 16 cSt, more preferably about 9 cSt to about 15 cSt. Hydrocarbonsynthetic oils may include, for example, oils prepared from thepolymerization of ethylene, i.e., polyalphaolefin or PAO, or fromhydrocarbon synthesis procedures using carbon monoxide and hydrogengases such as in a Fisher-Tropsch process. A preferred base oil is onethat comprises little, if any, heavy fraction; e.g., little, if any,lube oil fraction of viscosity 20 cSt or higher at 100 degrees C.

The base oil may be derived from natural lubricating oils, syntheticlubricating oils or mixtures thereof. Suitable base oil includes basestocks obtained by isomerization of synthetic wax and slack wax, as wellas hydrocrackate base stocks produced by hydrocracking (rather thansolvent extracting) the aromatic and polar components of the crude.Suitable base oils include those in all API categories I, II, III, IVand V as defined in API Publication 1509, 14th Edition, Addendum I,December 1998. Saturates levels and viscosity indices for Group I, IIand III base oils are listed in Table 1. Group IV base oils arepolyalphaolefins (PAO). Group V base oils include all other base oilsnot included in Group I, II, III, or IV. Although Group II, III and IVbase oils are preferred for use in this invention, these preferred baseoils may be prepared by combining one or more of Group I, II, III, IVand V base stocks or base oils. TABLE 1 Saturates, Sulfur and ViscosityIndex of Group I, II and III Base Stocks Saturates (As determined byViscosity Index ASTM D 2007) (As determined Sulfur by ASTM D 4294, (Asdetermined by ASTM D 4297 or Group ASTM D 2270) ASTM D 3120) I Less than90% Greater than or saturates and/or Greater equal to 80 and than to0.03% sulfur less than 120 II Greater than or equal to Greater than or90% saturates and less equal to 80 and than or equal to 0.03% less than120 sulfur III Greater than or equal to Greater than or 90% saturatesand less equal to 120 than or equal to 0.03% sulfur

Natural lubricating oils may include animal oils, vegetable oils (e.g.,rapeseed oils, castor oils and lard oil), petroleum oils, mineral oils,and oils derived from coal or shale.

Synthetic oils may include hydrocarbon oils and halo-substitutedhydrocarbon oils such as polymerized and inter-polymerized olefins,alkylbenzenes, polyphenyls, alkylated diphenyl ethers, alkylateddiphenyl sulfides, as well as their derivatives, analogues andhomologues thereof, and the like. Synthetic lubricating oils alsoinclude alkylene oxide polymers, interpolymers, copolymers andderivatives thereof wherein the terminal hydroxyl groups have beenmodified by esterification, etherification, etc. Another suitable classof synthetic lubricating oils comprises the esters of dicarboxylic acidswith a variety of alcohols. Esters useful as synthetic oils also includethose made from C₅ to C₁₂ monocarboxylic acids and polyols and polyolethers. Tri-alkyl phosphate ester oils such as those exemplified bytri-n-butyl phosphate and tri-iso-butyl phosphate are also suitable foruse as base oils.

Silicon-based oils (such as the polyakyl-, polyaryl-, polyalkoxy-, orpolyaryloxy-siloxane oils and silicate oils) comprise another usefulclass of synthetic lubricating oils. Other synthetic lubricating oilsinclude liquid esters of phosphorus-containing acids, polymerictetrahydrofurans, polyalphaolefins, and the like.

The base oil may be derived from unrefined, refined, rerefined oils, ormixtures thereof. Unrefined oils are obtained directly from a naturalsource or synthetic source (e.g., coal, shale, or tar sand bitumen)without further purification or treatment. Examples of unrefined oilsinclude a shale oil obtained directly from a retorting operation, apetroleum oil obtained directly from distillation, or an ester oilobtained directly from an esterification process, each of which may thenbe used without further treatment. Refined oils are similar to theunrefined oils except that refined oils have been treated in one or morepurification steps to improve one or more properties. Suitablepurification techniques include distillation, hydrocracking,hydrotreating, dewaxing, solvent extraction, acid or base extraction,filtration, and percolation, all of which are known to those skilled inthe art. Rerefined oils are obtained by treating used oils in processessimilar to those used to obtain the refined oils. These rerefined oilsare also known as reclaimed or reprocessed oils and often areadditionally processed by techniques for removal of spent additives andoil breakdown products.

Base oil derived from the hydroisomerization of wax may also be used,either alone or in combination with the aforesaid natural and/orsynthetic base oil. Such wax isomerate oil is produced by thehydroisomerization of natural or synthetic waxes or mixtures thereofover a hydroisomerization catalyst.

It is preferred to use a major amount of base oil in the lubricating oilof this invention. A major amount of base oil as defined hereincomprises 40 wt. % or more. Preferred amounts of base oil comprise about40 wt. % to about 97 wt. % of at least one of Group II, III and IV baseoil or preferably greater than about 50 wt. % to about 97 wt. % of atleast one of Group II, III and IV base oil or more preferably about 60wt. % to about 97 wt. % of at least one of Group II, III and IV baseoil. (When wt. % is used herein, it is referring to wt. % of thelubricating oil unless otherwise specified.) A more preferred embodimentof this invention may comprise an amount of base oil that comprisesabout 85 wt. % to about 95 wt. % of the lubricating oil.

The amount of benzo[b]perhydroheterocyclic compounds of the presentinvention in the lubricating oil composition will be in a minor amountcompared to the base oil of lubricating viscosity. Generally, it will bein an amount from about 0.01 to 10 wt %, preferably from about 0.1 toabout 2.0 wt %, more preferably from about 0.3 to about 1.8 wt % andeven more preferably from about 0.5 to about 1.5 wt %, based on thetotal weight of the lubricating oil composition.

The following additive components are examples of components that can befavorably employed in combination with the lubricating additive of thepresent invention. These examples of additives are provided toillustrate the present invention, but they are not intended to limit it.

(A) Ashless dispersants: alkenyl succinimides, alkenyl succinimidesmodified with other organic compounds such as ethylene carbonate,polysuccinimides, and alkenyl succinimides modified with boric acid,alkenyl succinic ester.

(B) Oxidation inhibitors:

1) Phenol type phenolic oxidation inhibitors:4,4′-methylenebis(2,6-di-tert-butylphenol),4,4′-bis(2,6-di-tert-butylphenol),4,4′-bis(2-methyl-6-tert-butylphenol),2,2′-(methylenebis(4-methyl-6-tert-butyl-phenol)),4,4′-butylidenebis(3-methyl-6-tert-butylphenol),4,4′-isopropylidenebis(2,6-di-tert-butylphenol),2,2′-methylenebis(4-methyl-6-nonylphenol),2,2′-isobutylidene-bis(4,6-dimethylphenol),2,2′-methylenebis(4-methyl-6-cyclohexylphenol),2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol,2,4-dimethyl-6-tert-butyl-phenol, 2,6-di-tert-α-dimethylamino-p-cresol,2,6-di-tert-4(N,N′dimethylaminomethylphenol),4,4′-thiobis(2-methyl-6-tert-butylphenol),2,2′-thiobis(4-methyl-6-tert-butylphenol),bis(3-methyl-4-hydroxy-5-tert-butylbenzyl)-sulfide, andbis(3,5-di-tert-butyl-4-hydroxybenzyl).

2) Other types: metal dithiocarbamate (e.g., zinc dithiocarbamate), andmethylenebis(dibutyldithiocarbamate).

(C) Rust inhibitors (Anti-rust agents):

1) Nonionic polyoxyethylene surface active agents: polyoxyethylenelauryl ether, polyoxyethylene higher alcohol ether, polyoxyethylenenonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethyleneoctyl stearyl ether, polyoxyethylene oleyl ether, polyoxyethylenesorbitol monostearate, polyoxyethylene sorbitol mono-oleate, andpolyethylene glycol monooleate.

2) Other compounds: stearic acid and other fatty acids, dicarboxylicacids, metal soaps, fatty acid amine salts, metal salts of heavysulfonic acid, partial carboxylic acid ester of polyhydric alcohol, andphosphoric ester.

(D) Demulsifiers: addition product of alkylphenol and ethyleneoxide,polyoxyethylene alkyl ether, and polyoxyethylene sorbitane ester.

(E) Extreme pressure agents (EP agents), sulfurized oils, diphenylsulfide, methyl trichlorostearate, chlorinated naphthalene, benzyliodide, fluoroalkylpolysiloxane, and lead naphthenate.

(F) Friction modifiers: fatty alcohol, fatty acid, amine, borated ester,and other esters

(G) Multifunctional additives: sulfurized oxymolybdenum dithiocarbamate,sulfurized oxymolybdenum organo phosphorodithioate, oxymolybdenummonoglyceride, oxymolybdenum diethylate amide, amine-molybdenum complexcompound, and sulfur-containing molybdenum complex compound

(H) Viscosity Index improvers: polymethacrylate type polymers,ethylene-propylene copolymers, styrene-isoprene copolymers, hydratedstyrene-isoprene copolymers, polyisobutylene, and dispersant typeviscosity index improvers.

(I) Pour point depressants: polymethyl methacrylate.

(K) Foam Inhibitors: alkyl methacrylate polymers and dimethyl siliconepolymers.

(L) Wear inhibitors: zinc dialkyldithiophosphate (Zn-DTP, primary alkyltype & secondary alkyl type).

General Synthetic Procedures

The benzo[b]perhydroheterocyclic arylamines of this invention may beprepared by the following general methods and procedures. It should beappreciated that where typical or preferred process conditions (e.g.,reaction temperatures, times, mole ratios of reactants, solvents,pressures, etc.) are given; other process conditions may also be usedunless otherwise stated. Optimum reaction conditions may vary with theparticular reactants or solvents used, but such conditions can bedetermined by one skilled in the art by routine optimization procedures.

Those skilled in the art will also recognize that it may be necessary toblock or protect certain functional groups while conducting thefollowing synthetic procedures. In such cases, the protecting group willserve to protect the functional group from undesired reactions or toblock its undesired reaction with other functional groups or with thereagents used to carry out the desired chemical transformations. Theproper choice of a protecting group for a particular functional groupwill be readily apparent to one skilled in the art. Various protectinggroups and their introduction and removal are described, for example, inT. W. Greene and P. G. M. Wuts, Protective Groups in Organic Synthesis,Second Edition, Wiley, New York, 1991, and references cited therein.

Synthesis

The benzo[b]perhydroheterocyclic arylamines of the present invention areprepared by reduction of benzo[b]heterocyclic arylamines as illustratedin sequence (I).

The benzo[b]heterocyclic arylamines may be prepared by the reactionsequences depicted in (II) and (III)

wherein R₁, R₂, R₃, n, X and X′ are as defined herein and Z is —OH,—NH₂, Cl, Br or I.

The coupling reactions shown in (II) and (III) are known in the art forthe synthesis of diphenylamines. These coupling methods are applicableto the synthesis of benzo[b]heterocyclic arylamines. Particularlynoteworthy coupling reactions for the synthesis of anilinoquinolines aredescribed by Buu-Hoi, Royer and Hubert-Habart, J. Chem. Soc., 1956,2048-2051 and Okada, Suzuki, Hirose, Toda and Ozawa, Chem. Commun.,2001, 2492-2493. Buchwald and Hartwig have developed a palladiumcatalyzed coupling of aromatic amines and aromatic halides which isapplicable to the synthesis of benzo[b]heterocyclic arylamines (Wolfe,Wagaw, Marcoux and Buchwald, Acc. Chem. Res., 1998, 805-818 andreferences cited therein and J. C. Peters, S. B. Harkins, S. D. Brownand M. D W. Day, Inorg. Chem., 2001, 40, 5083-5091). A copper catalyzedmethod has been developed by Patil, Kelkar, Nabi, and Chaudhari, Chem.Commun., 2003, 2460-2461.

There are several methods to reduce the benzo[b]heterocyclic arylaminesto benzo[b]perhydroheterocyclic arylamines. The methods that can beemployed are the same as those for the reduction of quinoline totetrahydroquinoline provided that any functionality which is sensitivetowards reduction is protected. Hydrogenation can be used as describedfor quinolines in Rylander, Catalytic Hydrogenation in OrganicSynthesis, 1979, 213-230, Academic Press. Hydrogenation of quinolines totetrahydroquinolines as well as other methods of reduction is describedin Hudlicky, Reductions in Organic Chemistry Second Edition, 1996,72-74, American Chemical Society. 6-aminoquinoline has been hydrogenatedto 6-aminotetrahydroquinoline with a platinum oxide catalyst in Example2 of WO 92/05173. The reduction of quinolines to tetrahydroquinolineswith sodium borohydride—nickelous chloride is described by Nose andKudo, Chem. Pharm. Bull., 1984, 32, 2421-2425. The reduction ofquinolines to tetrahydroquinolines with sodium borohydride in acidicmedia is described by Gribble and Heald, Synthesis, 1975, 650-652.

EXAMPLES

The invention is further illustrated by the following examples, whichare not to be considered as limitative of its scope. A furtherunderstanding of the invention can be had in the following nonlimitingPreparations and Examples. Wherein unless expressly stated in thecontraty, all temperatures and temperatures ranges refer to theCentigrade system and the term “ambient” or “room temperature” refers toabout 20 to 25° C. The term “percent or %” refers to weight percent, andthe term “mole” or “moles” refers to gram moles. The term “equivalent”refers to a quantity of reagent equal in moles, to the moles of thepreceding or succeeding reactant recited in that example in terms offinite moles or finite weight or volume. Where given, proton-magneticresonance spectrum (p.m.r. or n.m.r) were determined at 300 mHz, signalsare assigned as singlets(s), braod singlets (bs), doublets (d), doubledoublets (dd), triplets (t), double triplets (dt), quartets (q), andmultiplets (m), and cps refers to cycles per second.

Example 1 Preparation of Phenyl-(1,2,3,4-tetrahydro-quinolin-6-yl)-amine

A solution of 20.4 grams of 6-anilinoquinoline (prepared as described inBuu-Hoi, Royer and Hubert-Habart, J. Chem. Soc., 1956, 2048-2051) in 400mL of acetic acid containing 1.3 grams of platinum(IV) oxide washydrogenated at 30 psi for 4.2 hours on a Parr low-pressurehydrogenator. The solution was filtered; and the filtrate wasneutralized with 6N aqueous sodium hydroxide. The aqueous phase wasextracted three times with dichloromethane. The combined dichloromethanelayers were washed with 6N aqueous sodium hydroxide followed by brine.The dichloromethane layer was dried over anhydrous magnesium sulfate,filtered and concentrated in vacuo to yield 20.4 grams of a darkresidue. The dark residue was recrystallized from 95% ethanol to yield15.2 grams of the desired product as a grey solid. ¹H NMR (CDCl₃) δ 7.2(m, 2H), 6.8 (m, 4H), 6.45 (d, 1H), 5.35 (bs, 1H), 3.4 (bs, 1H), 3.25(t, 2H), 2.75 (t, 2H), 1.95 (p, 2H).

Example 2 Step A—Preparation of N-(4-tert-butylphenyl)quinolin-8-amine

To a flask equipped with a magnetic stirrer, reflux condensor, andnitrogen inlet was added 8-aminoquinoline (14.4 grams, 0.10 moles),4-tert-butyl bromobenzene (21.3 grams, 0.10 moles),tris(dibenzylideneacetone)dipalladium (0) (1.8 grams, 0.002 moles),rac-2,2′-bis(diphenylphosphino)-1,1′-binapthyl (2.5 grams, 0.004 moles),sodium tert-butoxide (19.4 grams, 0.20 moles) and anhydrous toluene (150mL). The contents of the flask were refluxed for four days; cooled toroom temperature; and filtered through a pad of silica gel. The silicagel pad was then eluted with dichloromethane (240 mL). The combinedorganic layers were concentrated in vacuo to yield a dark blue solid.The solid was chromatographed on silica gel, eluting with hexane/ethylacetate (20:1) to afford 23 grams of the desired product as a yellowsolid. ¹H NMR (CDCl₃) □ 8.8 (m, 1H), 8.2 (bs, 1H), 8.1 (d, 1H), 7.1-7.5(m, 9H), 1.35 (s, 9H).

Step B—Preparation ofN-(4-tert-butylphenyl)-1,2,3,4-tetrahydroquinolin-8-amine

A solution of 2.46 grams of N-(4-tert-butylphenyl)quinolin-8-amine fromStep A in 100 mL of acetic acid containing 0.15 grams of platinum(IV)oxide was hydrogenated at 45 psi for 1.5 hours on a Parr low-pressurehydrogenator. The solution was filtered through diatomaceous earth;concentrated in vacuo; and neutralized with 3N aqueous sodium hydroxide.The aqueous phase was diluted with water and extracted three times withethyl acetate. The combined ethyl acetate layers were washed with brine;dried over anhydrous magnesium sulfate, filtered and concentrated invacuo to yield 2.5 grams of dark blue oil. The oil was chromatographedon silica gel, eluting with hexane/ethyl acetate (20:1) to afford 2.0grams of the desired product as a yellow oil. ¹H NMR (CDCl₃) δ 7.2 (d,2H), 6.5-6.95 (m, 5H), 4.95 (bs, 1H), 3.3 (t, 2H), 2.8 (t, 2H), 1.9 (p,2H), 1.3 (s, 9H).

Example 3

aa

Step A—Preparation of N-2-naphthylquinolin-6-amine

To a flask equipped with a magnetic stirrer, reflux condensor, andnitrogen inlet was added 6-aminoquinoline (6.69 grams, 46.4 mmoles),2-bromonapthalene (9.15 grams, 44.2 mmoles),tris(dibenzylideneacetone)dipalladium (0) (0.80 grams, 0.87 mmoles),rac-2,2′-bis(diphenylphosphino)-1,1′-binapthyl (1.10 grams, 1.77mmoles), sodium tert-butoxide (8.49 grams, 88.3 mmoles) and anhydroustoluene (90 mL). The contents of the flask were refluxed for five hours;cooled to room temperature; and filtered through a pad of silica gel.The silica gel pad was then eluted with tetrahydrofuran (135 mL). Thecombined organic layers were concentrated in vacuo to yield a brownsolid. The solid was recrystallized from ethanol to afford 8.6 grams ofthe desired product as a yellow solid. ¹H NMR (DMSO-d₆/D₂O) δ 8.9 (d,1H), 8.65 (d, 1H), 8.2 (d, 1H), 7.25-8.05 (m, 10H).

Step B—Preparation of N-2-naphthyl-1,2,3,4-tetrahydroquinolin-6-amine

A solution of 7.00 grams of N-2-naphthylquinolin-6-amine from above inacetic acid (60 mL) and ethyl acetate (10 mL) containing 0.55 grams ofplatinum(IV) oxide was hydrogenated at 45 psi for 6.0 hours on a Parrlow-pressure hydrogenator. The solution was filtered throughdiatomaceous earth; concentrated in vacuo; and neutralized with 3Naqueous sodium hydroxide. The aqueous phase was diluted with water andextracted three times with ethyl acetate. The combined ethyl acetatelayers were washed with brine; dried over anhydrous magnesium sulfate,filtered and concentrated in vacuo to yield 5.5 grams solid. The solidwas chromatographed on silica gel, eluting with hexane/ethyl acetategradient to afford 3.5 grams of the desired product as a yellow solid.¹H NMR (CDCl₃/D₂O) δ 6.4-7.8 (m, 10H), 3.1-3.5 (m, 2H), 2.6-2.9 (m, 2H),1.95 (p, 2H).

Example 4 Step A—Preparation of N-2-naphthylquinolin-8-amine

To a flask equipped with a magnetic stirrer, reflux condensor, andnitrogen inlet was added 8-aminoquinoline (6.81 grams, 47.2 mmoles),2-bromonapthalene (9.58 grams, 46.3 mmoles),tris(dibenzylideneacetone)dipalladium (0) (0.84 grams, 0.92 mmoles),rac-2,2′-bis(diphenylphosphino)-1,1′-binapthyl (0.6 grams, 0.92 mmoles),sodium tert-butoxide (8.86 grams, 92.2 mmoles) and anhydrous toluene (90mL). The contents of the flask were refluxed for sixteen hours; cooledto room temperature; and filtered through a pad of silica gel. Thesilica gel pad was then eluted with dichloromethane (135 mL). Thecombined organic layers were concentrated in vacuo to yield a yellowsolid. The solid was chromatographed on silica gel, eluting with ahexane/ethyl acetate gradient to afford 6.6 grams of the desired productas a yellow solid. ¹H NMR (CDCl₃) δ 8.75 (d, 1H), 8.4 (bs, 1H), 8.05 (d,1H), 7.6-7.9 (m, 5H), 7.25-7.5 (m, 5H), 7.2 (d, 1H).

Step B—Preparation of N-2-naphthyl-1,2,3,4-tetrahydroquinolin-8-amine

A solution of 4.08 grams of N-2-naphthylquinolin-8-amine from above inacetic acid (10 mL) and ethyl acetate (150 mL) containing 0.24 grams ofplatinum(IV) oxide was hydrogenated at 45 psi for four hours on a Parrlow-pressure hydrogenator. The solution was filtered throughdiatomaceous earth; concentrated in vacuo; and neutralized with 3Naqueous sodium hydroxide. The aqueous phase was diluted with water andextracted three times with ethyl acetate. The combined ethyl acetatelayers were washed with brine; dried over anhydrous magnesium sulfate,filtered and concentrated in vacuo to yield 4.2 grams of the desiredproduct as a purple oil. ¹H NMR (CDCl₃/D₂O) δ 7.7 (m, 2H), 7.6 (d, 1H),7.35 (t, 1H), 7.25 (m, 1H), 7.05 (m, 2H), 6.9 (m, 2H), 6.6 (t, 1H), 3.3(t, 2H), 2.85 (t, 2H), 1.95 (p, 2H).

Example 5 Preparation ofN-(4-tert-butylphenyl)-2,3-dihydro-1-benzofuran-5-amine

To a flask equipped with a magnetic stirrer, reflux condensor, andnitrogen inlet was added 2,3-dihydro-1-benzofuran-5-amine (11.6 grams,85.8 mmoles, prepared as in Example 23 of U.S. Pat. No. 20040029932),4-tert-butyl bromobenzene (18.1 grams, 85 mmoles),tris(dibenzylideneacetone)dipalladium (0) (1.6 grams, 1.7 mmoles),rac-2,2′-bis(diphenylphosphino)-1,1′-binapthyl (2.1 grams, 3.4 mmoles),sodium tert-butoxide (16.4 grams, 0.17 moles) and anhydrous toluene (100mL). The contents of the flask were refluxed for three days; cooled toroom temperature; and filtered through a pad of silica gel. The silicagel pad was then eluted with dichloromethane (150 mL). The combinedorganic layers were concentrated in vacuo to yield a dark solid. Thesolid was chromatographed on silica gel, eluting with hexane/ethylacetate (20:1) to afford 10 grams of the desired product as a whitesolid. ¹H NMR (CDCl₃) δ 7.25 (d, 2H), 6.95 (s, 1H), 6.85 (d, 3H), 6.7(d, 1H), 5.4 (bs, 1H), 4.5 (t, 2H), 3.15 (t, 2H), 1.3 (s, 9H).

Example 6 Preparation ofN′-(2,3-dihydro-1-benzofuran-5-yl)-N,N-diethylbenzene-1,4-diamine

To a flask equipped with a magnetic stirrer, reflux condensor, andnitrogen inlet was added N,N-diethyl-1,4-phenylenediamine (3.35 grams,20.4 mmoles), 5-bromo-2,3-dihydrobenzofuran (3.4 grams, 17.1 mmoles),tris(dibenzylideneacetone)dipalladium (0) (0.39 grams, 0.43 mmoles),rac-2,2′-bis(diphenylphosphino)-1,1′-binapthyl (2.1 grams, 3.4 mmoles),sodium tert-butoxide (0.71 grams, 1.28 mmoles) and anhydrous toluene (90mL). The contents of the flask were heated to 80° C. for two days;cooled to room temperature; and filtered through a pad of silica gel.The silica gel pad was then eluted with dichloromethane (200 mL). Thecombined organic layers were concentrated in vacuo to yield a dark blueoil. The oil was chromatographed on silica gel, eluting with ahexane/ethyl acetate gradient to afford 4.2 grams of the desired productas a brown oil. ¹H NMR (CDCl₃) δ 6.6-7.0 (m, 7H), 5.15 (bs, 1H), 4.5 (t,2H), 3.05-3.2 (m, 6H), 1.1 (t, 6H).

Example 7 Preparation ofN-(4-tert-butylphenyl)-2,3-dihydro-1,4-benzodioxin-6-amine

To a flask equipped with a magnetic stirrer, reflux condensor, andnitrogen inlet was added 1,4-benzodioxin-6-amine (5.26 grams, 34.8mmoles), 4-tert-butyl bromobenzene (6.83 grams, 32.1 mmoles),tris(dibenzylideneacetone)dipalladium (0) (0.58 grams, 0.6 mmoles),rac-2,2′-bis(diphenylphosphino)-1,1′-binapthyl (0.79 grams, 1.2 mmoles),sodium tert-butoxide (6.08 grams, 63.0 mmoles) and anhydrous toluene (70mL). The contents of the flask were refluxed for three days; cooled toroom temperature; and filtered through a pad of silica gel. The silicagel pad was then eluted with dichloromethane (300 mL). The combinedorganic layers were concentrated in vacuo to yield a dark solid. Thesolid was chromatographed on silica gel, eluting with a hexane/ethylacetate gradient to afford 5 grams of the desired product as a whitesolid. ¹H NMR (CDCl₃) δ 7.25 (d, 2H), 6.9 (d, 2H), 6.75 (d, 1H), 6.5-6.7(m, 2H), 5.4 (bs, 1H), 4.2 (s, 4H), 1.3 (s, 9H).

Example 8 Preparation ofN-(4-butylphenyl)-1,2,3,4-tetrahydroquinolin-8-amine

To a flask equipped with a magnetic stirrer, reflux condenser, andnitrogen inlet was added 8-hydroxyquinoline (20.0 grams, 0.14 moles),4-butyl aniline (24.0 grams, 0.16 moles) and iodine (0.52 grams, 2.0mmoles). The contents of the flask were refluxed for eight days; cooledto room temperature; and diluted with toluene. The toluene solution wasfiltered through diatomaceous earth and further diluted withdichloromethane. The solution was washed with 5% aqueous sodiumhydroxide three times and water three times. The organic layer was driedover magnesium sulfate, filtered and concentrated in vacuo to yield adark brown oil. The oil was chromatographed on silica gel, eluting withhexane/ethyl acetate (10:1) to afford 3.7 grams a brown oil.

The oil in 70 mL of acetic acid containing 0.22 grams of platinum(IV)oxide was hydrogenated at 35 psi for 4.5 hours on a Parr low-pressurehydrogenator. The solution was filtered; and the filtrate wasneutralized with 6N aqueous sodium hydroxide. The aqueous phase wasextracted three times with dichloromethane. The combined dichloromethanelayers were washed with 6N aqueous sodium hydroxide followed by brine.The dichloromethane layer was dried over anhydrous magnesium sulfate,filtered and concentrated in vacuo to yield 3.9 grams of a dark brownoil. The oil was chromatographed on silica gel, eluting with ahexane/ethyl acetate gradient to afford 2.1 grams of the desired productas a yellow oil ¹H NMR (CDCl₃) δ 7.05 (d, 2H), 6.95 (d, 1H), 6.80 (d,1H), 6.70 (d, 2H), 6.6 (t, 1H), 4.95 (bs, 1H), 4.05 (bs, 1H), 3.3 (t,2H), 2.8 (t, 2H), 2.5 (t, 2H), 1.95 (p, 2H), 1.55 (p, 2H), 1.35(h, 2H),0.95 (t, 3H).

Performance Examples

Oxidation studies of the products of selected Examples were carried outin a bulk oil oxidation bench test as described by E. S. Yamaguchi etal. in Tribology Transactions, Vol. 42(4), 895-901 (1999). In this testthe rate of oxygen uptake at constant pressure by a given weight of oilwas monitored. The time required (induction time) for rapid oxygenuptake per 25 grams of sample was measured at 171° C. under 1.0atmosphere of oxygen pressure. The sample was stirred at 1000revolutions per minute. The results are reported, however, as time forrapid oxygen uptake per 100 grams of sample. The oil contained acatalyst added as oil soluble naphthenates to provide 26 ppm iron, 45ppm copper, 512 ppm lead, 2.3 ppm manganese, and 24 ppm tin.

The screening formulation was a fully formulation lubricating oilcomposition and contained in a Group 2+base oil, 7.0 mmoles/kg dialkylzinc dithiophosphate, 4.0% polyisobutenyl succinimide, 0.5%dinonyldiphenylamine, 0.25% polyisobutenyl succinimide containing 5.5%molybdenum, 48.5 mmoles/kg overbased calcium sulfonate detergent and0.3% V.I. improver. This baseline screening formulation was tested inthe oxidation bench and had a result of 14.1 hours to rapid O₂ uptake.To the baseline screening formulation was top treated with an additionalcompound and tests were performed at two concentrations. The compoundsand results of the oxidation bench test are presented in Table 1. TABLE1 Oxidation Bench Test of Benzo[b]perhydroheterocyclic compounds TestResults (Hr to Rapid)O₂ uptake Performance Compound of (Concentration ofAntioxidant) Example Example # (0.5 wt %) (1.0 wt %) 1 1 55.5 125.0 2 252.9 94.5 3 3 68.2 146.5 4 4 80.8 152.0 5 5 49.0 62.0 6 6 33.1 61.0 7 744.0 68.0 8 8 85.0 111.0 Comparative A¹ 32.5 41.0 A Comparative B² 41.983.5 BA¹ - Irganox ® L57 (diphenylamine alkylated with 2,4,4-trimethylpentene)available commercially from Ciba-GeigyB² - 4-(2-octylamino)diphenylamine available from TCI America

The excellent oxidation inhibition performance of Examples 1-8 isdemonstrated at 0.5 wt % addition to the base line screening formulationand a 1.0 wt % addition to the base line screening formulation. As canbe seen from the Table, there is a dramatic improvement by the additionof a small amount of the compounds of the present invention over thebase line screening formulation. More dramatically, is when thecompounds in Performance Examples 1-8 is compared to Comparative ExampleA (a commercially available product) an alkylated diphenylamine, whichshows up to a 3× improvement in performance, as shown in the Table. Thebenzo[b]perhydroheterocyclic amines of the Performance Examples 1-4 and8 also perform better than the non cyclic amine in Comparative Example B(a commercially available product). The advantages on oxidationinhibition can be seen when constraining a heteroatom into a ring.

1. A compound according to formula I:

wherein R₁ and R₂ are each independently selected from the groupconsisting of hydrogen, alkyl from 1 to 20 carbon atoms, —OR, —SR and—NRR′, where R and R′ are independently hydrogen or alkyl from 1 to 6carbon atoms, or R₁ and R₂ when adjacent to each other together form a 5to 6 membered alicyclic or aromatic ring which may be optionallysubstituted with 1 or 2 alkyl groups each having from 1 to 20 carbonatoms; each R₃ is hydrogen or alkyl from 1 to 6 carbon atoms, X and X′are independently selected from —CHR₄—, oxygen, sulfur or NR₅, whereinR₄ and R₅ are independently hydrogen or alkyl from 1 to 6 carbon atoms,with the proviso that at least one of X or X′ is a heteroatom positionedortho or para to the bridging nitrogen atom, and when X or X′ arenitrogen then R₁ or R₂ is not hydroxyl; and further provided that whenone of X or X′ is —CHR₄— then the other may not be oxygen; and n is aninteger from 1 to
 2. 2. The compound according to claim 1 wherein atleast one X and X′ are selected from NR₅ and oxygen.
 3. The compoundaccording to claim 2, wherein at least one X and X′ is NR₅.
 4. Thecompound according to claim 3, wherein X is —CHR₄— and X′ is NR₅.
 5. Thecompound according to claim 4, wherein n is
 2. 6. The compound accordingto claim 5, wherein R₃, R₄ and R₅ are each hydrogen.
 7. The compoundaccording to claim 4, wherein R₁ and R₂ are each independently selectedfrom the group consisting of hydrogen, alkyl from 1 to 20 carbon atoms,or R₁ and R₂ when adjacent to each other together form a 5 to 6 memberedalicyclic or aromatic ring which may be optionally substituted with 1 or2 alkyl groups each having from 1 to 20 carbon atoms.
 8. The compoundaccording to claim 7, wherein R₁ and R₂ are each independently selectedfrom the group consisting of hydrogen and alkyl from 1 to 20 carbonatoms.
 9. The compound of claim, 1, wherein at least one X and X′ issulfur.
 10. The compound of claim 1, wherein X and X′ are independentlyselected from oxygen, sulfur or NR₅, wherein R₅ is hydrogen or alkylfrom 1 to 6 carbon atoms.
 11. The compound of claim 10, wherein X and X′are oxygen.
 12. The compound according to claim 1, wherein R₃ ishydrogen.
 13. The compound according to claim 1, wherein R₁ and R₂ areadjacent to each other and together form a 5 to 6 membered aromatic ringwhich may be optionally substituted with 1 or 2 alkyl groups each havingfrom 1 to 20 carbon atoms.
 14. The compound according to claim 1,wherein R₁ is hydrogen and R₂ is selected from the group consisting ofalkyl from 1 to 20 carbon atoms, —OR, —SR and —NRR′, where R and R′ areindependently hydrogen or alkyl from 1 to 6 carbon atoms.
 15. Thecompound according to claim 14, wherein R₂ is —NRR′ where R and R′ arealkyl from 1 to
 6. 16. A lubricating composition comprising a majoramount of an oil of lubricating viscosity and a compound according toformula I:

wherein R₁ and R₂ are each independently selected from the groupconsisting of hydrogen, alkyl from 1 to 20 carbon atoms, —OR, —SR and—NRR′, where R and R′ are independently hydrogen or alkyl from 1 to 6carbon atoms, or R₁ and R₂ when adjacent to each other together form a 5to 6 membered alicyclic or aromatic ring which may be optionallysubstituted with 1 or 2 alkyl groups each having from 1 to 20 carbonatoms; each R₃ is hydrogen or alkyl from 1 to 6 carbon atoms, X and X′are independently selected from —CHR₄—, oxygen, sulfur or NR₅, whereinR₄ and R₅ are independently hydrogen or alkyl from 1 to 6 carbon atoms,with the proviso that at least one of X or X′ is a heteroatom positionedortho or para to the bridging nitrogen atom, and when X or X′ arenitrogen then R₁ or R₂ is not hydroxyl; and further provided that whenone of X or X′ is —CHR₄— then the other may not be oxygen; and n is aninteger from 1 to
 2. 17. The lubricating composition according to claim16 wherein at least one X and X′ are selected from NR₅ and oxygen. 18.The lubricating composition according to claim 17, wherein at least oneX and X′ is NR₅.
 19. The lubricating composition according to claim 18,wherein X is —CHR₄— and X′ is NR₅.
 20. The lubricating compositionaccording to claim 19, wherein n is
 2. 21. The lubricating compositionaccording to claim 20, wherein R₃, R₄ and R₅ are each hydrogen.
 22. Thelubricating composition according to claim 20, wherein R₁ and R₂ areeach independently selected from the group consisting of hydrogen, alkylfrom 1 to 20 carbon atoms, or R₁ and R₂ when adjacent to each othertogether form a 5 to 6 membered alicyclic or aromatic ring which may beoptionally substituted with 1 or 2 alkyl groups each having from 1 to 20carbon atoms.
 23. The lubricating composition according to claim 22,wherein R₁ and R₂ are each independently selected from the groupconsisting of hydrogen and alkyl from 1 to 20 carbon atoms.
 24. Thelubricating composition of claim 16, wherein at least one X and X′ issulfur.
 25. The lubricating composition of claim 16, wherein X and X′are independently selected from oxygen, sulfur or NR₅, wherein R₅ ishydrogen or alkyl from 1 to 6 carbon atoms.
 26. The lubricatingcomposition of claim 25, wherein X and X′ are oxygen.
 27. Thelubricating composition according to claim 16, wherein R₃ is hydrogen.28. The lubricating composition according to claim 16, wherein R₁ and R₂are adjacent to each other and together form a 5 to 6 membered aromaticring which may be optionally substituted with 1 or 2 alkyl groups eachhaving from 1 to 20 carbon atoms.
 29. The lubricating compositionaccording to claim 16, wherein R₁ is hydrogen and R₂ is selected fromthe group consisting of alkyl from 1 to 20 carbon atoms, —OR, —SR and—NRR′, where R and R′ are independently hydrogen or alkyl from 1 to 6carbon atoms.
 30. The lubricating composition according to claim 16,wherein R₂ is —NRR′ where R and R′ are alkyl from 1 to 6.